Like all vitamins, B12 is a substance that our body can’t make for itself but needs in small but vital amounts that we get from our diet. Vitamin B12 is most abundant in meat, fish, eggs and dairy products. As you can see from this list, vitamin B12 can be lacking from vegetarian and vegan diets and, as these types of diet have become more popular, vitamin B12 deficiency has become more common.

Vitamin B12 is very important for making red blood cells and for the health of the nervous system, particularly the nerves that supply sensation to the hands and feet. This means that B12 deficiency can lead to anaemia and to neuropathy, but it’s central importance to our health means that milder deficiency can cause a raft of debilitating symptoms. These include memory problems, fatigue, low mood, visual disturbance, a sore tongue and mouth ulcers, as well as the symptoms of anaemia which include shortness of breath, pallor, feeling faint and palpitations, and the symptoms of neuropathy which include tingling, numbness and pain which usually starts in the feet and slowly progresses up the legs and arms.

Given the wide range of symptoms that may be caused by a deficiency in B12, it is no wonder that many people are interested to check their levels and that doctors check B12 levels for a huge array of different complaints.

Checking vitamin B12 is very simple, it’s just a blood test. But how vitamin B12 deficiency is treated depends on a number of different factors.

For most people, B12 deficiency is due to a lack of the vitamin in their diet. A low B12 may be detected by chance as apart of a routine blood test, or it may be done whilst looking for a cause of difficult to define symptoms such as fatigue or malaise. If B12 deficiency is due to a lack of the vitamin in the diet then vitamin B12 can be increased by changing your diet, or by taking vitamin supplements which are readily available from pharmacies, supermarkets, and health food shops. Taking these steps will usually bring B12 levels back to normal and improve your symptoms. It is worth rechecking your vitamin B12 levels a couple of months after taking supplements or changing your diet to make sure that your levels have improved as expected.

The consequences of B12 deficiency that we tend to worry about most are neuropathy (which usually starts with numbness, tingling or pain in the feet) and anaemia (which is identified by finding that you have low haemoglobin). If you already have these problems, and are found to have low vitamin B12, then it is usually recommended that you have your vitamin B12 replaced more intensively with a series of injections, six of which are given over two weeks. This is roughly an injection every other day for two weeks. This intensive replacement can often rapidly reverse your symptoms and prevent them from getting worse.

A small minority of people have vitamin B12 deficiency because they have a condition known as ‘pernicious anaemia’. In pernicious anaemia there is a problem with the lining of the stomach which prevents you from properly absorbing vitamin B12. This means that, no matter how much B12 you eat or how many oral supplements you take, your B12 probably won’t improve to normal levels. Pernicious anaemia is rare but it can run in families, and it is more common in people with other autoimmune conditions such as type 1 diabetes or thyroid disorders.

If you have pernicious anaemia, you will need to have your vitamin B12 replaced by an injection that is usually given every 3 months. Pernicious anaemia is diagnosed by checking for an autoantibody called ‘intrinsic factor’ in people who have been found to have low vitamin B12 levels.

Vitamin B12 deficiency can cause a wide range of problems but it is easily checked for and easily treated, even if you have underlying pernicious anaemia.